Rios is bigger; I'd think he hits harder. He came in at 160lbs his last fight with Alvarado, at least if I got the numbers right. I don't know what Pacquiao rehydrates to at this point probably 149lbs.
My impression is Rios has more 'thudding' power but Manny has 'sharper' power ie Rios' body punches will hurt more but Pac will see his head punches coming whereas Rios probably won't see Pac... assuming the Pac we know and love turns up. It's def a real fight for Pac. He loses this one and he's done. Hopefully for his sake his religion will allow him to put him the KO behind him. I could believe that, he seemed pretty accepting after the KO but then he's had time to stew on it since then.
This new UberMarquez is the hardest puncher Manny has faced. Margarito is second. Cotto is probably in third place. Rios hit really hard at 135, and appears to hit somewhat hard at 140. His power is unproven at 147, but I doubt it will improve up there. I don't think Alvarado hits harder than Manny either. I think Rios is going to get trashed unless his chin is Roy Jones-level gone when he comes back. Rios got rocked by Alvarado in the second fight when he ate up everything Alvarado threw at him in the first fight. I think this might be evidence his chin is already deteriorating. There are question marks around the chins of both fighters, and further questions regarding whether or not Pac has much left in the tank.
Ive never seen no man stunn Cast ironed jaw Margarito with just 1 punch . Not even Shane did that . Gotta go with Pacman , He got more punching power .
I would say Cotto and Margarito have equal power . Margarito is just a lot more agressive and relentless .